melcepst.txt

DTW+VQ实现的语音识别 UIUC提供

function c=melcepst(s,fs,w,nc,p,n,inc,fl,fh)
%MELCEPST Calculate the mel cepstrum of a signal C=(S,FS,W,NC,P,N,INC,FL,FH)
%
%
% Simple use: c=melcepst(s,fs)  % calculate mel cepstrum with 12 coefs, 256 sample frames
%                                 c=melcepst(s,fs,'e0dD') % include log energy, 0th cepstral coef, delta and delta-delta coefs
%
% Inputs:
%     s  speech signal
%     fs  sample rate in Hz (default 11025)
%     nc  number of cepstral coefficients excluding 0'th coefficient (default 12)
%     n   length of frame (default power of 2 <30 ms))
%     p   number of filters in filterbank (default floor(3*log(fs)) )
%     inc frame increment (default n/2)
%     fl  low end of the lowest filter as a fraction of fs (default = 0)
%     fh  high end of highest filter as a fraction of fs (default = 0.5)
%
%               w   any sensible combination of the following:
%
%                               'R'  rectangular window in time domain
%                               'N'     Hanning window in time domain
%                               'M'     Hamming window in time domain (default)
%
%                     't'  triangular shaped filters in mel domain (default)
%                     'n'  hanning shaped filters in mel domain
%                     'm'  hamming shaped filters in mel domain
%
%                               'p'     filters act in the power domain
%                               'a'     filters act in the absolute magnitude domain (default)
%
%                          '0'  include 0'th order cepstral coefficient
%                               'e'  include log energy
%                               'd'     include delta coefficients (dc/dt)
%                               'D'     include delta-delta coefficients (d^2c/dt^2)
%
%                     'z'  highest and lowest filters taper down to zero (default)
%                     'y'  lowest filter remains at 1 down to 0 frequency and
%                                 highest filter remains at 1 up to nyquist freqency
%
% Outputs:      c     mel cepstrum output: one frame per row
%


%      Copyright (C) Mike Brookes 1997
%
%      Last modified Thu Jun 15 09:14:48 2000
%
%   VOICEBOX is a MATLAB toolbox for speech processing. Home page is at
%   http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%   This program is free software; you can redistribute it and/or modify
%   it under the terms of the GNU General Public License as published by
%   the Free Software Foundation; either version 2 of the License, or
%   (at your option) any later version.
%
%   This program is distributed in the hope that it will be useful,
%   but WITHOUT ANY WARRANTY; without even the implied warranty of
%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%   GNU General Public License for more details.
%
%   You can obtain a copy of the GNU General Public License from
%   ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if nargin<2 fs=11025; end
if nargin<3 w='M'; end
if nargin<4 nc=12; end
if nargin<5 p=floor(3*log(fs)); end
if nargin<6 n=pow2(floor(log2(0.03*fs))); end
if nargin<9
   fh=0.5;   
   if nargin<8
     fl=0;
     if nargin<7
        inc=floor(n/2);
end
  end
end

if any(w=='R')
   z=enframe(s,n,inc);
elseif any (w=='N')
   z=enframe(s,hanning(n),inc);
else
   z=enframe(s,hamming(n),inc);
end
f=rfft(z.');
[m,a,b]=melbankm(p,n,fs,fl,fh,w);
pw=f(a:b,:).*conj(f(a:b,:));
pth=max(pw(:))*1E-6;
if any(w=='p')
   y=log(max(m*pw,pth));
else
   ath=sqrt(pth);
   y=log(max(m*abs(f(a:b,:)),ath));
end
c=rdct(y).';
nf=size(c,1);
nc=nc+1;
if p>nc
   c(:,nc+1:end)=[];
elseif p